System for imaging in the air

ABSTRACT

A system for imaging in the air including an image source, a transflector, and a retroreflective element. Light rays emitted by the image source are reflected by the transflector to irradiate on the retroreflective element, and are subjected to reflection on the retroreflective element, before being emitted along an original incident path in an opposite direction and being transmitted through the transflector to form a real image. By means of the present system, it is possible to directly present images in the air, even in vacuum, without the aid of any medium.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/398,194, filed on Jan. 4, 2017, which claims priority to CNApplication No. 2016111240031, filed on Dec. 8, 2016, the entirecontents of which are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The embodiments of the present invention relate to the field ofholographic imaging, and more particularly to a system for imaging inthe air.

BACKGROUND OF THE DISCLOSURE

Holography is a technology of recording and reproducing a realthree-dimensional image of an object by means of interference anddiffraction principles.

A conventional holographic imaging method is to produce holographicimages using the principle of laser interference. Light emitted by alaser source is divided into two beams, one of which irradiates directlytowards a photosensitive film and the other of which is reflected by anobject to be shot before irradiating towards the photosensitive film.The two beams of light are superimposed on the photosensitive film toproduce interference. Finally, the reproduced hologram is furtherprocessed according to the basic principle of digital images to removedigital interference, thereby obtaining a clear holographic image. Thismethod has the disadvantages of strict monochromatic requirement andgreat difficulty in realization of color imaging.

Existing holographic imaging technologies are generally classified intothe following three types.

The first type depends on virtual reality or augmented reality glassesor helmet, such as Microsoft's HoloLens, etc. This type of technologyhas limited application scenarios and currently high costs, due to aneed for dependence on auxiliary instrument.

The second type, in dependence on a reflector in high-speed rotation anda projector with high-speed refreshing, is projecting an image on thereflector in high-speed rotation so as to realize a three-dimensionalimage. The patent document CN105372926A discloses a rotary holographicprojection display cabinet utilizing such technology. This technologycan hardly achieve interaction, and has very harsh requirements forspace.

The third type, in dependence on medium containing fine particles, suchas air comprising water vapor, is projecting an image on small waterdroplets formed by liquefaction of the water vapor. Due to molecularvibration disparity, an image with a strong sense of hierarchy andstereoscopic vision can be formed. The patent documents CN104977794A andCN103116422A disclose application of such technology, both using a watervapor curtain wall to form an image in the air. Application of suchtechnology still involves a need to be equipped with auxiliary tools,for the production of a water vapor curtain wall. Thus, it is not quiteconvenient to use the third type of technology.

In general, the above technologies, which are imaging in virtual realityor augmented reality tools, imaging in a reflector in high-speedrotation, or imaging in vapor particles in the air, is not imaging inthe air in a true sense.

SUMMARY OF THE EMBODIMENTS OF THE PRESENT INVENTION

The embodiments of the present invention, which aim to overcome thedeficiencies of the technologies described above, provides a true systemand method of imaging in the air, enabling imaging directly in the airwithout any special medium, or even imaging in vacuum. This greatlybroadens the range of applications, is no longer restricted by auxiliarytools, and brings a revolutionary breakthrough to an existinghuman-computer interaction scenario.

In accordance with an aspect of the present invention, a system forimaging in the air is providedthat includes an image source, atransflector and an retroreflective element, wherein, light rays emittedby the image source are reflected by the transflector to irradiate onthe retroreflective element, and are subjected to reflection on theretroreflective element, before being emitted along an original incidentpath in an opposite direction and being transmitted through thetransflector to form a real image.

In accordance with another aspect of the present invention, a system forimaging in the air is providedthat includes an image source, atransflector, and an retroreflective element, wherein, light raysemitted by the image source are transmitted through the transflector toirradiate on the retroreflective element, and are subjected toreflection on the retroreflective element, before being emitted along anoriginal incident path in an opposite direction and being reflected bythe transflector to form a real image.

According to yet another aspect of the present invention, a system forimaging in the air is providedthat includes an image source, atransflector, a first retroreflective element and a secondretroreflective element, wherein, light rays emitted by the image sourceare reflected by the transflector to irradiate on the firstretroreflective element, and are subjected to reflection on the firstretroreflective element, before being emitted along an original incidentpath in an opposite direction and being transmitted through thetransflector to form a first real image; and additionally, the lightrays emitted by the image source are transmitted through thetransflector to irradiate on the second retroreflective element, and aresubjected to reflection on the second retroreflective element, beforebeing emitted along an original incident path in an opposite directionand being reflected by the transflector to form a second real image.

In accordance with another aspect of the present invention, a system forimaging in the air is providedthat includes a first image source, asecond image source, a transflector, and an retroreflective element,wherein, light rays emitted by the first image source are reflected bythe transflector to irradiate on the retroreflective element, and aresubjected to reflection on the retroreflective element, before beingemitted along an original incident path in an opposite direction andbeing transmitted through the transflector to form a first real image;light rays emitted by the second image source are transmitted throughthe transflector to irradiate on the retroreflective element, and aresubjected to reflection on the retroreflective element, before beingemitted along an original incident path in an opposite direction andbeing reflected by the transflector to form a second real image; andpositions of the first image source and the second image source areconfigured so that the first real image and the second real image areformed at a same position.

Preferably, the image sources are imaging devices that emit virtualimages or real images, or virtual images or real images formed by thesedevices.

Preferably, the light source of the image source is one or more of alaser, a light-emitting diode, an organic light-emitting diode, and astimulated fluorescent light-emitting material.

Preferably, transmittance of the transflector is in the range of about20% to about 80%.

Preferably, reflectance of the transflector is in the range of about 20%to about 80%.

In a preferred embodiment, the retroreflective element comprises asubstrate with a reflective face, and a microstructure disposed on thesubstrate.

Preferably, the microstructure is a right-angle vertex microstructuremade of a transparent material, wherein the right-angle vertexmicrostructure has at least one right-angle vertex whose three edges areat right angles to each other.

Preferably, the microstructure is a recess containing a right-anglevertex microstructure, where the right-angle vertex microstructure hasat least one right-angle vertex whose three edges are at right angles toeach other.

Preferably, the microstructure is a spherical microstructure made of atransparent material.

Preferably, the reflective face is formed on a face of the substratefacing the microstruture.

Preferably, the reflective face is formed at an interface of thesubstrate and the microstructure.

Preferably, the microstructure and the substrate are integrally formedby the same transparent material, the right-angle vertex protrudesoutwardly and the reflective face is formed on three faces formed in amanner that the three edges of the right-angle vertex intersect eachother.

Preferably, the microstructure is uniformly distributed over thesubstrate.

Preferably, the substrate is a film, a curtain or a plate.

In another preferred embodiment, the retroreflective element includes aplurality of retroreflective units.

Preferably, the retroreflective units include a microstructure with areflective face.

Preferably, the microstructure is a right-angle vertex microstructuremade of a transparent material, where the right-angle vertexmicrostructure has at least one right-angle vertex whose three edges areat right angles to each other, and three faces formed in a manner thatthe three edges intersect each other or at least their partial regionsform the reflective face.

Preferably, the microstructure is a recess containing a right-anglevertex microstructure, where the right-angle vertex microstructure hasat least one right-angle vertex whose three edges are at right angles toeach other, and three faces formed in a manner that the three edgesintersect each other or at least their partial regions form thereflective face.

Preferably, the microstructure is a spherical microstructure made of atransparent material, where a part of surface of the sphericalmicrostructure, more distant from the transflector, forms a reflectiveface.

Preferably, the reflective face of the microstructure is attached to orformed integrally with a substrate, where the substrate can be used tocarry the retroreflective element.

Preferably, a face other than the reflective face of the microstructureis attached to or formed integrally with a transparent substrate, wherethe substrate can be used to carry the retroreflective element.

In yet another preferred embodiment, the retroreflective element alsoincludes a plurality of retroreflective units.

Preferably, the retroreflective units include one of a first materialand a second material, and the retroreflective units further include areflective face, where, the first material is a transparent solidmaterial; the first material, as viewed from an incident path of thelight rays, is positioned in front of the reflective face, and the lightrays are incident through the first material and then are reflected bythe reflective face, before being further emitted from the firstmaterial; and the second material, as viewed from the incident path ofthe light rays, is positioned rearward of the reflective face.

Preferably, the retroreflective units comprise a first material and asecond material, and the retroreflective units further comprise areflective face, wherein, the first material is air or vacuum, and thesecond material is a film, a curtain or a plate; the first material, asviewed from the incident path of the light rays, is positioned in frontof the reflective face, and the light rays are incident through thefirst material and then are reflected by the reflective face, beforebeing further emitted from the first material; and the second material,as viewed from the incident path of the light rays, is positionedrearward of the reflective face.

Preferably, the reflective face is three faces formed in a manner thatthree edges of the right-angle vertex intersect each other or at leasttheir partial regions, wherein the three edges of the right-angle vertexare at right angles to each other.

Preferably, the reflective face is a part of a surface of a sphere, andthe center of the sphere is positioned in front of the reflective face,as viewed from the incident path of the light rays.

Preferably, the second material is a film, a curtain or plate.

Preferably, the three edges of the right-angle vertex are of equallength.

Preferably, the reflective face is attached with a highly reflectivematerial.

Preferably, the reflectance of the highly reflective material is morethan 60%, 70%, 80%, or 90%.

Preferably, the highly reflective material is attached on the reflectiveface by spray coating or filming.

Preferably, the retroreflective element has a curvature bent towards thetransflector.

Preferably, the microstructure is uniformly distributed over theretroreflective element.

Preferably, the image source is a stereoscopic image source.

Preferably, the stereoscopic image source is a three-dimensionalstereoscopic display device that can display three-dimensionalstereoscopic images, structures, and video sources.

Preferably, the three-dimensional stereoscopic display device includes atranslational scan imaging system or a rotational scan imaging system.

Preferably, one of two faces of the transflector is attached with atransflective material such that the reflectance is between about 20%and about 80% and corresponding transmittance is between about 80% andabout 20%.

Preferably, the face of the two faces of the transflector, which is notattached with a transflective material, is attached with anantireflective material.

Preferably, the three edges each have a length between about 5 mm andabout 20 mm.

Preferably, the longest edge length of the three edges does not exceed10 times the shortest edge length.

Preferably, when the first material is a transparent solid material, itsincidence face is attached with an antireflection material.

Preferably, when the first material is a transparent solid material, itsincident face is a plane.

Preferably, at least one of three faces formed by the three edges has anangle of less than 54 degrees from the incident face.

According to a major of the present invention, a method for imaging inthe air is provided that includes the steps of providing an imagesource, a transflector and a retroreflective element; reflecting, by thetransflector, light rays emitted by the image source, to irradiate onthe retroreflective element; and subjecting the light rays to reflectionon the retroreflective element, before being emitted along an originalincident path in an opposite direction and being transmitted through thetransflector to form a real image.

According to another aspect of the present invention, a method forimaging in the air is providedthat includes the steps of providing animage source, a transflector and a retroreflective element;transmitting, through the transflector, light rays emitted by the imagesource, to irradiate on the retroreflective element; and subjecting thelight rays to reflection on the retroreflective element, before beingemitted along an original incident path in an opposite direction andbeing reflected by the transflector to form a real image.

According to yet another aspect of the present invention, a method forimaging in the air is providedthat includes the steps of providing animage source, a transflector, a first retroreflective element and asecond retroreflective element; reflecting, by the transflector, lightrays emitted by the image source, to irradiate on the firstretroreflective element, and transmitting, through the transflector, thelight rays emitted by the image source, to irradiate on the secondretroreflective element; subjecting the light rays to reflection on thefirst retroreflective element, before being emitted along an originalincident path in an opposite direction and being transmitted through thetransflector to form a first real image, and subjecting the light raysto reflection on the second retroreflective element, before beingemitted along an original incident path in an opposite direction andbeing reflected by the transflector to form a second real image.

According to another aspect of the present invention, a method forimaging in the air is providedthat includes the steps of providing afirst image source, a second image source, a transflector, and anretroreflective element; reflecting, by the transflector, light raysemitted by the first image source, to irradiate on the retroreflectiveelement, and transmitting, through the transflector, light rays emittedby the second image source, to irradiate on the retroreflective element;subjecting the light rays emitted by the first image source toreflection on the retroreflective element, before being emitted along anoriginal incident path in an opposite direction and being transmittedthrough the transflector to form a first real image, and subjecting thelight rays emitted by the second image source to reflection on theretroreflective element, before being emitted along an original incidentpath in an opposite direction and being reflected by the transflector toform a second real image; and configuring positions of the first imagesource and the second image source, such that the first real image andthe second real image are formed at substantially the same position. Aperson of ordinary skill in the art will readily understand that apositioning tolerance for the first and second real images isacceptable, as long as the two images are close enough not to bedistinguished by human eyes.

The embodiments of the present invention innovatively utilizes e.g., aretroreflective film and a transflective mirror in combination totransform a virtual image into a real image, thereby realizing imagingin the air. Advantages of the embodiments of the present inventionare:images can be presented directly in air, even in vacuum, without the aidof any medium (e.g., screen, gas or liquid containing fine particles,etc.); several persons can view the images at the same time, without theaid of other auxiliary equipment such as helmets, glasses, etc.; and inaddition, the images are floating in the air, and can be toucheddirectly by hands, thus making it impossible to extend a lot ofinteractive applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description,will be better understood when read in conjunction with the appendeddrawings. For the purpose of illustration, there is shown in thedrawings certain embodiments of the present disclosure. It should beunderstood, however, that the invention is not limited to the precisearrangements and instrumentalities shown. The accompanying drawings,which are incorporated in and constitute a part of this specification,illustrate an implementation of systems and apparatuses consistent withthe present invention and, together with the description, serve toexplain advantages and principles consistent with the invention. Thesedrawings are not to be construed as limiting the invention, but areillustrative.

FIG. 1 schematically shows an imaging system according to an embodimentof the present invention;

FIG. 2 schematically shows an imaging system according to anotherembodiment of the present invention;

FIG. 3 schematically shows a retroreflective element according to anembodiment of the present invention;

FIG. 4 schematically shows a microstructure of a retroreflective elementand a retroreflective path according to an embodiment of the presentinvention;

FIG. 5 schematically shows a retroreflective element according toanother embodiment of the present invention;

FIGS. 6A, 6B and 6C schematically show a microstructure of aretroreflective element and a retroreflective path according to anotherembodiment of the present invention;

FIG. 7 schematically shows a retroreflective element according to yetanother embodiment of the present invention;

FIG. 8 schematically shows a microstructure of a retroreflective elementand a retroreflective path according to yet another embodiment of thepresent invention; and

FIG. 9 schematically shows a top view of distribution of amicrostructure of a retroreflective element according to an embodimentof the present invention.

FIG. 10 schematically shows an imaging system according to furtheranother embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE PRESENT INVENTION

In order to make the object, technical solutions and advantages of thepresent invention clearer, the present invention will be furtherdescribed in detail with reference to the accompanying drawings.

For purposes of descriptive brevity and intuition, the followingdisclosure will illustrate the solutions of the present invention bydescribing a number of representative embodiments. Numerous details inthe embodiments are provided solely to aid in understanding thesolutions of the present invention. However, it is quite apparent thatthe technical solutions of the present invention, when inimplementation, are allowed not to be confined to these details. Inorder to avoid unnecessarily obscuring the solutions of the presentinvention, some embodiments will not be described in detail, but only aframework is presented. In the following disclosure, “comprise(include)” means “include, but is not limited to”, and “according to (inaccordance with) . . . ” means “at least according to (in accordancewith) . . . , but is not limited to only according to . . . ”. The words“first”, “second” and the like are used only for reference to features,and are not intended to impose any limitation on the features, such aslimitation on sequence. Owing to language conventions of the Chineselanguage, when the following disclosure does not particularly specifythe number of a component, it is meant that the component can be one ormore in number, or can be understood as at least one.

FIG. 1 shows an imaging system according to an embodiment of the presentinvention. As shown in FIG. 1, the system comprises an image source 1, atransflector 2 and a retroreflective element 3. The plane at which thetransflector 2 is located divides space into a first semi-region I and asecond semi-region II; and both the image source 1 and theretroreflective element 3 are in the first semi-region I.

Light rays emitted by the image source 1 are reflected by thetransflector 2 to irradiate on the retroreflective element 3. The lightrays are subjected to retroreflection on the retroreflective element 3so that reflected light rays on the retroreflective element 3 and theincident light rays utilize the same path and simply are opposite indirections. Thus, after being reflected by the retroreflective element3, the light rays are emitted along an original incident path (it shouldbe understood, from a microscopic view, it can be considered that thereflective path and the incident path are slightly offset from eachother; however, from a macroscopic view, it can be considered that thetwo paths are totally coincident), and are then transmitted through thetransflector, to form a real image 4 in the second semi-region II.

The image source 1 can be image displaying devices, and can also be avirtual image or a real image formed by these image displaying devices.

For example, the image displaying device can be a liquid crystal screen,and a backlight light source of the liquid crystal screen includes oneor more of a laser, a light emitting diode, an organic light emittingdiode, a stimulated fluorescent light emitting material, and a quantumdot stimulation light source. The image displaying device can also be alattice screen which is formed by light-emitting point light sourcessuch as LED, OLED, and plasma light emitting point and emits light onits own. The image displaying device may also be a projection imagingsystem in which light, driven by light sources such as LED, OLED, laserand fluorescence, or a combination thereof, is reflected by ortransmitted through display panels such as DMD, LCOS and LCD, and thenprojected on the projection screen via projecting lens for imaging onthe basis of projection techniques such as DLP, LCOS and LCD. The imagedisplaying device can also be a projection imaging system in which laserbeams scan and image on the screen. Moreover, in all the imagedisplaying devices described above, a real image or virtual image formedby one or more refractions or reflections may also be used as an imagesource.

In preferred embodiments, the image source 1 may be a stereoscopic imagesource. The stereoscopic image source includes a three-dimensionalstereoscopic display device which can display 3D stereoscopic images,structures, and video sources. The three-dimensional stereoscopicdisplay device generally comprises a control module and a high-speedprojection module or a high-speed display module. The control module isconfigured to control the projection module or the display module toproject or display a series of 2D image slices at high speed to aplurality of optical planes, such that an observer observes athree-dimensional stereoscopic image, structure, or video. Thethree-dimensional stereoscopic display device includes a translationalscan imaging system, a rotational scan imaging system, and the like.

The transflector may be made of a variety of suitable transparentmaterials, such as PC resin, PET resin, PMMA resin, glass, quartz andthe like. The transmittance of the transflector is between about 20% andabout 80%, preferably, about 50%. The reflectance of the transflector isalso between about 20% and about 80%, preferably, also about 50%. Aperson of ordinary skill in the art will readily understand that theword “about” means plus or minus 10% of the numerical value it modifies.

The retroreflective element 3 is preferably a thin film, curtain or aplate distributed with a microstructure, which preferably has acurvature bent towards the transflector, thereby making it possible toincrease the brightness of the resulted image. The following disclosurewill describe in detail the retroreflective element 3.

Referring to FIG. 2, in another embodiment of the present invention, thesystem comprises an image source 1, a transflector 2 and aretroreflective element 3. The plane at which the transflector 2 islocated divides space into a first semi-region I and a secondsemi-region II. The image source 1 is located at the first semi-regionI, whereas the retroreflective element 3 is located at the secondsemi-region II.

Light rays emitted by the image source 1 are transmitted through thetransflector 2 to irradiate on the retroreflective element 3. The lightrays are subjected to retroreflection on the retroreflective element 3so that reflected light rays on the retroreflective element 3 and theincident light rays utilize the same path and simply are opposite indirections. Thus, after being reflected by the retroreflective element3, the light rays are emitted along an original incident path, and arethen reflected by the transflector, to form a real image 4 in the secondsemi-region II.

It is to be understood that, due to wave-particle duality of light,there is a certain diffraction effect when the light rays are reflectedfrom the retroreflective element 3, and a certain divergence angle isgenerated by the reflected light. When taking this into account, as longas the main axis of the reflected light and the incident light areopposite in directions, the meaning of “retroreflection” according tothe present invention is also satisfied.

In this embodiment, the light rays emitted by the image source 1 aretransmitted (not reflected by) through the reflector mirror 2, beforereaching the retroreflective element 3. The light rays reflected by theretroreflective element 3 are reflected (but not transmitted through) bythe transflector 2, to generate a real image 4. The finally generatedreal image 4 and the retroreflective element 3 are located at a samesemi-region, rather than at different semi-regions.

In one embodiment of the present invention (see FIG. 10), the twoembodiments described above are combined in a way of employing tworetroreflective elements 3′ and 3″, such that the light rays emitted bythe image source 1 are reflected by the transflector 2, before reachingone of the retroreflective elements 3′ and 3″; and the light raysreflected by the retroreflective element 3′ are further transmittedthrough the transflector 2 to generate a real image. The light raysemitted by the image source are transmitted through the transflector 2to reach the other retroreflective element 3″, and the light raysreflected by the other retroreflective element 3″ are further reflectedby the transflector 2, to generate a real image. As such, the twogenerated images overlap, thereby obtaining an image with greaterbrightness.

Of course, it should be understood that, in other embodiments,additionally or alternatively, two image sources may be used. In thiscase, it is necessary to adjust the positions of the two image sources,and the transflector and the retroreflective elements, so that thefinally generated real images overlap in space.

The retroreflective element of the present invention is a speciallytreated element comprising, e.g., a substrate coated with a highlyreflective coating, and, a retroreflective microstructure, e.g.,uniformly distributed on the substrate. The highly reflective coatinghas a reflectance of 60% or more, preferably more than 70%, 80%, or 90%.It should be appreciated that the highly reflective coating may also beattached to the substrate in other manners, such as, for example,filming.

Of course, the highly reflective coating may, for example, be attachedto the face of the microstructure facing the substrate, or to theinterface of the microstructure and the substrate.

It is to be understood that the distribution of the retroreflectivemicrostructure on the substrate may also be non-uniform, and uniformdistribution will have a better imaging effect. However, somedeliberately arranged non-uniform distribution may be used forparticular imaging purposes.

Referring to FIG. 3, there is shown an retroreflective element accordingto an embodiment of the present invention. The retroreflective element 3includes a film or a curtain as a substrate 30. The substrate 30 iscoated with a highly reflective coating. In addition, sphericalmicrostructures 31 are uniformly distributed on the substrate 30.

Referring to FIG. 4, there are shown an enlarged view of a sphericalmicrostructure and a schematic diagram of a retroreflective path.

Light rays are refracted from the transflector through an upper surfaceof a spherical microstructure 31 to irradiate towards a highlyreflective coating of a substrate 30. After being reflected, the lightrays irradiate back onto the upper surface of the sphericalmicrostructure 31 and are refracted again to irradiate towards thetransflector. The spherical microstructure 31 is structured so that thelight rays can be returned to the transflector almost via the originalpath (as previously described, it can be considered that the light rays,when viewed in a macroscopic environment, are returned just along theoriginal path).

Referring to FIG. 5, there is shown a retroreflective element accordingto another embodiment of the present invention. A substrate 30 of theretroreflective element 3 is also uniformly distributed with aright-angle vertex microstructure 31′. The right-angle vertexmicrostructure 31′ may be a transparent microstructured body, such as amicrocube or a microcuboid, which is embedded on the substrate 30 andhas at least one vertex whose three edges are at right angles to eachother, or a part thereof containing at least one vertex. Of course, theat least one vertex is embedded in the substrate 30 (see FIG. 6A). Insome embodiments, the right-angle vertex microstructure 31′ is amicro-triangular pyramid, with three edges at right angles to eachother, where the vertex is embedded in the substrate 30 (see FIG. 6B);preferably, a bottom face opposite to the vertex is flush with thesubstrate 30; and more preferably, an antireflective film is furtherattached to the bottom face. In a more preferred embodiment, at leastone of three faces formed by the three edges has an angle of less than54 degrees from the bottom face.

It should be understood that, the three edges can be of equal length,and certainly can be of unequal lengths. The lengths of the edges can beselected from between about 5 mm and about 20 mm. Preferably, thelongest edge length of the three edges does not exceed 10 times theshortest edge length.

It should also be understood that the three faces formed by the threeedges should also be perpendicular to each other, i.e., the dihedralangles between any two of the three faces each should be 90 degrees;however, due to the constraints of the art, even if these dihedralangles are not precisely 90 degrees, but within a processing tolerancerange of, for example, ±2 minutes (please verify), requirements of thepresent invention can also be satisfied.

In another embodiment, the right-angle vertex microstructure 31′ may bea recess formed by imprinting a portion of one of the vertices of theabove microstructured body on the substrate 30 (see FIG. 6C).

FIGS. 6A, 6B, and 6C show an enlarged view of the right-angle vertexmicrostructure and a schematic view of the retroreflective path in FIG.5. In the embodiments shown in FIGS. 6A and 6B, the right-angle vertexmicrostructure 31′ is a transparent microstructured body. Light rays arerefracted from the transflector through an incident surface (e.g., anupper surface) of the right-angle vertex microstructure 31′ to irradiatetoward a highly reflective coating of a film or curtain 30. After beingreflected three times, the light rays irradiate back onto the incidentsurface (for example, the upper surface) of the right-angle vertexmicrostructure 31′, and are refracted again to irradiate towards thetransflector. In the embodiment shown in FIG. 6C, the right-angle vertexmicrostructure 31′ is a depression, and after being transmitted throughor reflected by the transflector, the light rays are directly incidenton the depression, and are then reflected three times, beforeirradiating towards the transflector. The right-angle vertexmicrostructure 31′ is structured so that the light rays can be returnedto the transflector almost via the original path (likewise, it can beconsidered that the light rays, when viewed in a macroscopicenvironment, are returned just along the original path).

FIG. 7 shows a retroreflective element according to yet anotherembodiment of the present invention. Right-angle vertex microstructures31′ is uniformly distributed on the substrate 30′ of the retroreflectiveelement 3. The substrate 30′ itself is a transparent substrate, and theright-angle vertex microstructure 31′ is also a transparentmicrostructured body. The faces of the right-angle vertex microstructure31 that departs from the substrate 30′ are coated with a highlyreflective coating.

The right-angle vertex microstructure 31′ is preferably formedintegrally with the substrate 30′, and certainly, can also be producedseparately and then attached to the substrate 30′. In preferred cases,the material of the substrate 30′ and the material of the right-anglevertex microstructure 31′ are identical, or at least have a samerefractive index.

FIG. 8 shows an enlarged view of the right-angle vertex microstructureand a schematic diagram of the retroreflective path in FIG. 7. Lightrays are refracted from the transflector through an upper surface of thesubstrate 30′ to irradiate towards a highly reflective coating of theright-angle vertex microstructure 31′. After being reflected threetimes, the light rays irradiate back onto the upper surface of thesubstrate 30′ and are refracted again to irradiate towards thetransflector. The right-angle vertex microstructure 31′ is structured sothat the light rays can be returned to the transflector almost via theoriginal path (as previously described, it can be considered that thelight rays, when viewed in a macroscopic environment, are returned justalong the original path).

FIG. 9 schematically shows the top view of distribution ofmicrostructures on the retroreflective element according to oneembodiment of the present invention, to better understand thedistribution of the microstructures. As shown, a plurality ofmicrostructures are distributed by turns in proximity to one another,and extend over the retroreflective elements. It is to be understoodthat, FIG. 9 shows only a part of the retroreflective elements and themicrostructures may be distributed over the entire retroreflectiveelement. In addition, although the microstructures shown in FIG. 9 aredepressions similar to cuboids, it should be understood that the shapeof the microstructures is not limited thereto, and may be any of themicrostructures described above.

It should be appreciated that, in the present invention, although areflective face (e.g., a face coated with a highly reflective coating)of the retroreflective element is described as being a portion attachedto the substrate in most cases, it can also be considered that thereflective face is a portion attached to the microstructure. Forexample, the retroreflective element may be divided into a large numberof retroreflective units each of which includes a microstructure with areflective face; the microstructure can be a spherical microstructure ora right-angle vertex microstructure as described above; or, thereflective face can even also be described as a separate structure unit.For example, the retroreflective units each include a reflective face,and the reflective face can be attached to at least one of the firstmaterial and the second material thereon; and the reflective face can beformed by one or more faces of the aforementioned microstructure.

According to the embodiments of the present invention, it is possible todirectly image in the air, even in vacuum, without depending onauxiliary equipment such as helmet, or on an imaging screen or aparticulate medium in the air. The embodiments of the present inventionrelate to an air imaging technology in a true sense. Since the generatedimage suspends in the air, a lot of interactions and applications can beextended, which is of an epoch-making significance.

It is to be understood that the foregoing description of the disclosedembodiments will enable those skilled in the art to realize or use thepresent invention. It is to be understood that, the features disclosedin the above embodiments may be used alone or in combination, unlessotherwise specified. Modifications to these embodiments will be readilyapparent to those skilled in the art. General principles defined in thepresent disclosure can be implemented in other embodiments, withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention disclosed herein is not limited to thespecific embodiments disclosed, but is intended to cover modificationswithin the spirit and scope of the invention as defined by the appendedclaims.

The invention claimed is:
 1. A system for imaging in the air,comprising: an image source, a transflector, a first retroreflectiveelement, and a second retroreflective element, wherein an orthographicprojection of the first retroreflective element on a plane where thetransflector is located and an orthographic projection of the secondretroreflective element on the plane where the transflector is locatedare overlapped; a plurality of light rays emitted by the image sourceare directly irradiated on the transflector and reflected by thetransflector to irradiate on the first retroreflective element, and theplurality of light rays, which are irradiated on the firstretroreflective element, are subjected to reflection on the firstretroreflective element to propagate along an original incident path inan opposite direction, and be directly incident onto the transflector,and then to be transmitted through the transflector to form a first realimage at a viewing side of the system; an orthographic projection of thefirst retroreflective element on the plane where the transflector islocated at least partially overlaps the transflector; and additionally,the plurality of light rays emitted by the image source are directlyirradiated on the transflector and transmitted through the transflectorto irradiate on the second retroreflective element, and the plurality oflight rays, which are irradiated on the second retroreflective element,are subjected to reflection on the second retroreflective element topropagate along an original incident path in an opposite direction andbe directly incident on the transflector, and then the plurality oflight rays, which are incident on the transflector, are reflected by thetransflector to form a second real image at the viewing side of thesystem.
 2. The system of claim 1, wherein each of the firstretroreflective element and the second retroreflective element comprisesa plurality of retroreflective units.
 3. The system of claim 2, whereinthe retroreflective units comprise a microstructure with a reflectiveface.
 4. The system of claim 3, wherein the microstructure is aright-angle vertex microstructure made of a transparent material,wherein the right-angle vertex microstructure has at least oneright-angle vertex whose three edges are at right angles to each other,and three faces formed in a manner that the three edges intersect eachother or at least their partial regions form the reflective face.
 5. Thesystem of claim 4, wherein a face other than the reflective face of themicrostructure is attached to or formed integrally with a transparentsubstrate, wherein the substrate can be used to carry theretroreflective units; the three edges of the right-angle vertex are ofequal length.
 6. The system of claim 3, wherein the microstructure is arecess containing a right-angle vertex microstructure, wherein theright-angle vertex microstructure has at least one right-angle vertexwhose three edges are at right angles to each other, and three facesformed in a manner that the three edges intersect each other or at leasttheir partial regions form the reflective face.
 7. The system of claim3, wherein the microstructure is a spherical microstructure made of atransparent material, wherein a partial surface of the sphericalmicrostructure, more distant from the transflector, forms a reflectiveface.
 8. The system of claim 3, wherein the reflective face of themicrostructure is attached to or formed integrally with a substrate,wherein the substrate can be used to carry the retroreflective units. 9.The system of claim 2, wherein the retroreflective units comprise atleast one of a first material and a second material, and theretroreflective units further comprise a reflective face, wherein, thefirst material is a transparent solid material; the first material, asviewed from an incident path of the light rays, is positioned in frontof the reflective face, and the light rays are incident through thefirst material and then are reflected on the reflective face, beforebeing further emitted from the first material; and the second material,as viewed from the incident path of the light rays, is positionedrearward of the reflective face.
 10. The system of claim 9, wherein thesecond material is a film, a curtain or a plate.
 11. The system of claim9, wherein the reflective face is three faces formed in a manner thatthree edges of a right-angle vertex intersect each other or at leasttheir partial regions, wherein the three edges of the right-angle vertexare at right angles to each other; among the three edges of theright-angle vertex, the length of the longest edge does not exceed 10times that of the shortest edge.
 12. The system of claim 9, wherein thereflective face is a part of a surface of a sphere, and the center ofthe sphere is positioned in front of the reflective face, as viewed fromthe incident path of the light rays.
 13. The system of claim 2, whereinthe retroreflective units comprise a first material and a secondmaterial, and the retroreflective units further comprise a reflectiveface, wherein, the first material is air or vacuum, and the secondmaterial is a film, a curtain or a plate; the first material, as viewedfrom an incident path of the light rays, is positioned in front of thereflective face, and the light rays are incident through the firstmaterial and then are reflected on the reflective face, before beingfurther emitted from the first material; and the second material, asviewed from the incident path of the light rays, is positioned rearwardof the reflective face.
 14. The system of claim 1, wherein each of thefirst retroreflective element and the second retroreflective element hasa curvature bent toward the transflector.
 15. The system of claim 1,wherein each of the first retroreflective element and the secondretroreflective element comprises a substrate with a reflective face andmicrostructures uniformly disposed on the substrate; a reflectivity ofthe reflective face is larger than 90%.
 16. The system of claim 15,wherein each microstructure is a right-angle vertex microstructure madeof a transparent material, wherein the right-angle vertex microstructurehas at least one right-angle vertex whose three edges are at rightangles to each other; the microstructures and the substrate areintegrally formed by a same transparent material, the right-angle vertexprotrudes outwardly and the reflective face is formed on three planesformed in a manner that the three edges of the right-angle vertexintersect each other.
 17. The system of claim 15, wherein eachmicrostructure is a recess containing a right-angle vertexmicrostructure, wherein the right-angle vertex microstructure has atleast one right-angle vertex whose three edges are at right angles toeach other.
 18. The system of claim 15, wherein each microstructure is aspherical microstructure made of a transparent material.
 19. The systemof claim 15, wherein the reflective face is formed on a face of thesubstrate facing the microstructures, or is formed at an interface ofthe substrate and the microstructures.
 20. The system of claim 1,wherein each of the first retroreflective element and the secondretroreflective element comprises a substrate and a plurality ofmicrostructures on the substrate, the substrate and the plurality ofmicrostructures are integrally formed by a same material; the pluralityof microstructures are at a side of the substrate away from thetransflector.
 21. The system of claim 20, further comprising areflective coating, wherein the reflective coating is at a surface, thatis away from the substrate, of each of the plurality of microstructures;light that is irradiated on the each of the first retroreflectiveelement and the second retroreflective element is refracted by asurface, that is away from the plurality of microstructures, of thesubstrate to be irradiated on and reflected by the reflective coating,light that is reflected by the reflective coating is irradiated on andrefracted by the surface, that is away from the plurality ofmicrostructures, of the substrate and then propagated toward thetransflector.
 22. The system of claim 21, wherein each of the firstretroreflective element and the second retroreflective element is acurved retroreflective element, and a center of the curvedretroreflective element is at a side of an edge of the curvedretroreflective element away from the transflector.
 23. The system ofclaim 1, wherein each of the first retroreflective element and thesecond retroreflective element comprises a substrate and a plurality ofmicrostructures on the substrate; each microstructure is a right-anglevertex microstructure made of a transparent material; the right-anglevertex microstructure comprises at least one right-angle vertex, andthree edges, that intersect at the at least one right-angle vertex, ofthe right-angle vertex microstructure are at right angles to each other;and the transflector is made of one or more selected from PC resin, PETresin, PMMA resin, glass, quartz; a transmittance of the transflector is50%; a reflectance of the transflector is 50%.